The plot of residuals in Exercise 41 shows an outlier that wasn€™t as evident in the data. The outlier is September 2001. Clearly, this wasn€™t a typical month for air travel. Here are three models fit to this series, a single exponential smooth, a 12-point moving average, and the fitted values from the seasonal regression model of Exercise 41. Discuss how each deals with the outlier.

The remaining exercises require the use of statistics software. Statistics packages vary in their capabilities and in the default decisions that some make. As a result, depending upon which package you choose, your answers may differ from those in the back of the book.

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1,500,000 1,250,0 1,000,000 750,000 500, 1 20 40 60 0 100120 140160180 Month (Jan 1990 1) MAPE MAD 6412 MSO ต69905066 Npna05 Forecasts 750,000 1 20 40 60 80 100 120 140 160 180 Month (Jan 1990-1) Movirg aenge MAPE HAD 88231 HSO 9705890030 Forecass 960% P 1,250,000 1,000,000 750,000 500,000 CL 40 0 120 160 Month (Jan 1000 1)